The Effect of Long Distance Air-travel on Serum Viscosity and Prothrombin Time

ABSTRACT

BACKGROUND: Economy class syndrome is medically described as deep vein thrombosis, it is worldwide issued that Long-Distance Air-Travel is a risk factor for venous thromboemborism. Some study provides evidence and theoretical explanations for the hypothesis that long-distance is a risk factor for venous thromboembolism. The purpose of this study is to provide the useful prevention of venous thromboembolism for long-distance travelers in comparison to the effect of long distance air-travel on serum viscosity and prothrombin time between flight level and ground level. METHODS: Subjects selected healthy volunteers that had no abnormal findings in evaluation (alpha2-plasmin inhibitor, plasminogen, anti-thrombin III, protein C, protein S) for hypercoagulability. 5subjects (1 male, 4 females) had a seat on economy class of ground training facility designed for flight attendant and their activities limited as possible during about 8 hours at Sep. 16, 2001. Also, 5 subjects had a seat on the economy class of Asiana Airlines (B-777) from Sydney in Australia to Seoul in Korea at Mar. 3, 2002. In the flight, Actual flight altitude was 31,000 feet, cabin altitude was 4,800 feet and cabin temperature was 25degrees C. We have investigated the serum viscosity used by viscometer and prothrombin time. These data were analyzed statistically by General linear model (spsswin ver. 10.0). RESULTS: The results showed that there were no differcence between Flight Group and Ground Group statistically. However, the serum viscosity of flight group by position was some higher than ground group but these defference was not statistically significance (P=0.419). Also, the serum viscosity of flight group by time had a decreased trend but these trend was not statistically significance (P=0.061). The prothrombin time of flight group by position was some lower than ground group but these defference was not statistically significance (P=0.472). Also, the prothrombin time of ground group by time had a decreased trend but these trend was not statistically significance (P=0.217). CONCLUSION: This study shows the prediction to venous thrombosis more closely relates to prothrombin time than serum viscosity under immobilization to healthy people on the ground environment. Exercise is more useful method than hydration to prevent venous thrombosis on the ground environment. In the flight environment, we think that hydration is also useful method to prevent venous thrombosis because of more dry environment inside flying aircraft. But, this study was decreased serum viscosity between samples according to time. I think serum viscosity can be reduced by vibration effect inside flying aircraft. Serum viscosity and prothrombin time between samples according to position were not statistically significant. I think that risk for the healthy people is poorly quantified and possibly overestimated that long-distance air-travel is a risk factor for venous thromboembolism.